Otolaryngology Book

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Non-Sedating AntihistamineAka: Loratadine, Claritin, Cetirizine, Zyrtec, Fexofenadine, Allegra

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  1. See Also
    1. Antihistamine
  2. Indications
    1. Allergic Rhinitis
  3. Pathophysiology
    1. Second Generation Antihistamine
  4. Precautions
    1. Astemizole (Hismanal) and Terfenadine (Seldane)
      1. Prolong QT Interval
      2. Contraindicated with Erythromycin, Ketoconazole
      3. Resulted in fatal arrhythmias in multiple cases
  5. Advantages: Less sedating than other Antihistamines
    1. Fexofenadine (Allegra)
      1. Least sedating, even in higher doses
    2. Loratadine (Claritin)
      1. Sedating at higher doses
      2. Less potent than Allegra and Zyrtec
    3. Cetirizine (Zyrtec)
      1. May be sedating even at normally recommended doses
  6. Disadvantages
    1. Expensive!
  7. Efficacy
    1. Cetirizine and fexofenadine most effective agents
  8. Preparations
    1. Fexofenadine (Allegra)
      1. Adult Dose: 60 mg PO bid or 180 mg PO qd
      2. Child Dose (ages 6-11 years): 30 mg PO bid
      3. Low Sedation and highly effective (medical letter recommends as preferred agent)
    2. Loratadine (Claritin, OTC)
      1. Adult Dose (includes ages 6-11 years): 10 mg PO qd
      2. Child Dose (ages 2-5 years): 5 mg PO qd
    3. Cetirizine (Zyrtec, OTC)
      1. Adult Dose (includes ages 6-11): 5 or 10 mg PO qd
      2. Child Dose (ages 2-5 years): 2.5 or 5 mg qd
  9. Pregnancy and Lactation
    1. Claritin is pregnancy Class B
      1. Other meds are Class C or unknown
    2. Contraindicated in Lactation
  10. References
    1. Howarth (1999) J Allergy Clin Immunol 104:927
    2. Walsh (2001) Drugs 61:207
    3. (2001) Med Lett Drugs Ther 43(1103):35

Cetirizine (C0055147)

Definition (MSH)A potent second-generation histamine H1 antagonist that is effective in the treatment of allergic rhinitis, chronic urticaria, and pollen-induced asthma. Unlike many traditional antihistamines, it does not cause drowsiness or anticholinergic side effects.
Definition (NCI)Cetirizine is a metabolite of hydroxyzine and a selective peripheral histamine H1-receptor antagonist. It is used for symptomatic treatment of seasonal and perennial allergic rhinitis and for chronic urticaria. (NCI)
ConceptsOrganic Chemical (T109) , Pharmacologic Substance (T121)
EnglishCetirizine, CETIRIZINE PREPARATION
Spanishcetiricina, cetirizina
Parent ConceptsHydroxyzine (C0020404), Histamine H1 Antagonists (C0019592), [AH500] ANTIHISTAMINES, PIPERAZINE (C0973468), Histamine H1 Antagonists, Non-Sedating (C1136312)
SourcesMSH, NCI, NDFRT, PDQ, RXNORM, SCTSPA, SNOMEDCT, USPMG, VANDF
Derived from the NIH UMLS (Unified Medical Language System)


Loratadine (C0065180)

Definition (MSH)A second-generation histamine H1 receptor antagonist used in the treatment of allergic rhinitis and urticaria. Unlike most classical antihistamines (HISTAMINE H1 ANTAGONISTS) it lacks central nervous system depressing effects such as drowsiness.
Definition (NCI)A piperidine histamine H1-receptor antagonist with anti-allergic properties and without sedative effects. Loratadine blocks the H1 histamine receptor and prevents the symptoms that are caused by histamine activity on capillaries, bronchial smooth muscle, and gastrointestinal smooth muscle, including vasodilatation, increased capillary permeability, bronchoconstriction, and spasmodic contraction of gastrointestinal smooth muscle. Loratadine does not cross the blood-brain barrier and does not cause central nervous system effects.
ConceptsOrganic Chemical (T109) , Pharmacologic Substance (T121)
EnglishLoratadine, LORATADINE PREPARATION, Loratadine product
Spanishloratadina
Parent ConceptsCyproheptadine (C0010620), Histamine H1 Antagonists (C0019592), [AH900] ANTIHISTAMINES, OTHER (C0973471), Histamine H1 Antagonists, Non-Sedating (C1136312), Piperidine derivative (C1268914)
SourcesLNC, MSH, MTHFDA, NCI, NDFRT, RXNORM, SCTSPA, SNOMEDCT, VANDF
Derived from the NIH UMLS (Unified Medical Language System)


Zyrtec (C0162723)

ConceptsOrganic Chemical (T109) , Pharmacologic Substance (T121)
EnglishPfizer Brand of Cetirizine Dihydrochloride, Pfizer Consumer Healthcare Brand of Cetirizine Dihydrochloride, Reactine, UCB Brand of Cetirizine Dihydrochloride, UCB Pharma Brand of Cetirizine Dihydrochloride, United Drug Brand of Cetirizine Dihydrochloride, Voltric, Zirtek, Zyrtec
SourcesMSH, NCI, RXNORM
Derived from the NIH UMLS (Unified Medical Language System)


fexofenadine (C0296800)

Definition (NCI)A second generation, long-lasting selective histamine H1 receptor antagonist with antiinflammatory property. Fexofenadine is a highly selective and reversible competitor at peripheral H1 histamine receptors in the gastrointestinal (GI) tract, blood vessels, and bronchial smooth muscle. This agent interferes with mediators release from mast cells either by inhibiting calcium ion influx across mast cell/basophil plasma membrane or by inhibiting intracellular calcium ion release within the cells. In addition fexofenadine may also inhibit the late-phase allergic reaction by acting on leukotrienes or prostaglandins, or by producing an anti-platelet activating factor effect. Overall, this agent blocks the actions of endogenous histamine, thereby leads to temporary relief of the negative symptoms associated with histamine and achieve effects such as decreased vascular permeability, reduction of pruritus and localized smooth muscle relaxation.
ConceptsOrganic Chemical (T109) , Pharmacologic Substance (T121)
Englishfexofenadine, FEXOFENADINE PREPARATION
Spanishfexofenadina
Parent ConceptsHistamine H1 Antagonists (C0019592), Terfenadine (C0085173), [AH600] ANTIHISTAMINES, BUTYROPHENONE (C0973469), Histamine H1 Antagonists, Non-Sedating (C1136312), Piperidine derivative (C1268914)
SourcesMSH, NCI, NDFRT, RXNORM, SCTSPA, SNOMEDCT, USPMG, VANDF
Derived from the NIH UMLS (Unified Medical Language System)


Claritin (C0701055)

ConceptsOrganic Chemical (T109) , Pharmacologic Substance (T121)
EnglishClaritin
SourcesMSH, NCI, RXNORM
Derived from the NIH UMLS (Unified Medical Language System)


Allegra (C1110594)

ConceptsOrganic Chemical (T109) , Pharmacologic Substance (T121)
EnglishAllegra, Aventis Behring brand of fexofenadine hydrochloride, Aventis brand of fexofenadine hydrochloride, Aventis Pharma brand of fexofenadine hydrochloride, Hoechst brand of fexofenadine hydrochloride, Telfast
SourcesMSH, MTH, NCI, RXNORM
Derived from the NIH UMLS (Unified Medical Language System)


Histamine H1 Antagonists, Non-Sedating (C1136312)

Definition (MSH)A class of non-sedating drugs that bind to but do not activate histamine receptors (INVERSE AGONISM), thereby blocking the actions of histamine or histamine agonists. These antihistamines represent a heterogenous group of compounds with differing chemical structures, adverse effects, distribution, and metabolism. Compared to the early (first generation) antihistamines, these non-sedating antihistamines have greater receptor specificity, lower penetration of BLOOD-BRAIN BARRIER, and are less likely to cause drowsiness or psychomotor impairment.
ConceptsPharmacologic Substance (T121)
EnglishHISTAMINE ANTAGONISTS H 001 NON SEDATING, HISTAMINE H1 ANTAG NON SEDATING, Non-sedating antihistamine, Non-Sedating H1 Antihistamines, Second Generation Antihistamines, Second Generation H1 Antagonists
Spanishantihistaminico no sedante
Parent ConceptsHistamine H1 Antagonists (C0019592), Antihistamines (C0003360)
SourcesMSH, SCTSPA, SNOMEDCT, USPMG
Derived from the NIH UMLS (Unified Medical Language System)



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